Electrified vehicles include significant amounts of hardware dedicated to dissipating waste heat produced by onboard electrified systems. This waste heat is exchanged through coolant and various heat exchangers through the refrigeration system as well as to the ambient environment. In larger vehicles equipped with an auxiliary climate control systems, state of the art motor vehicles require two sets of coolant lines running to the back of the vehicle: one for the auxiliary heating system, and one for the electric vehicle (EV) cooling system. This adds significant cost, and importantly, extra weight which, in turn, reduces the electrified range of the electric vehicle.
Additionally, fully autonomous vehicles including, for example ride share vehicles of the future, incorporate additional electronics which produce even greater levels of waste heat to the point of becoming greater than the capacity of a single refrigeration system. As a result, full secondary refrigeration loops dedicated to cooling the electronics are being designed to maintain cabin comfort and the electronics in their proper operating temperature range.
This document relates to a closed loop auxiliary heating circuit that provides a new and improved solution to the waste heat problem characteristic of larger electric vehicles including, particularly, the autonomous vehicles of the future. That closed loop auxiliary heating circuit is not connected to the power train of the motor vehicle and its function is to cool the motor vehicle electronics and utilize the waste heat from those electronics to provide comfort to the cabin. Advantageously, such a closed loop auxiliary heating circuit functions to reduce the overall weight of the system by reducing one set of underbody heater lines and the associated coolant from the power train to the auxiliary climate system. This reduction of the underbody lines also improves the “external” package space and reduces the assembly complexity of the system.
In addition, a valve is provided to control the flow of coolant to the auxiliary heater core thereby allowing the closed loop auxiliary heating circuit to deliver the desired temperature of air to the cabin of the motor vehicle without the use of a blend door. This improves the internal package space required for the auxiliary climate system. This can be a substantial benefit given that the electronics package space required for the auxiliary climate system is in the same region of the motor vehicle as the auxiliary climate system. Utilizing the waste heat to cool the cabin also reduces the refrigeration work required of the refrigeration system in most ambient weather conditions. Advantageously this can lead to increases in the range of the electric motor vehicle.